To charge my GPS device, an HTC HD2, I have chosen after careful examination of all the offers, the famous e-Werk from B+M in Germany, with a very good reputation. This AC/DC converter connects quite easily to the Shimano built-in dynamo in the front wheel. Voltage and current can be set as needed. In my case it starts charging already when I do less than 10 KM/H

CONNECTION

the e-Werk comes with plenty of connectors for all kinds of GPS devices. My HTC HD2 has the latest sub-mini USB connector, which is also the (coming) standard in Europe for all mobile-chargers.

MOUNTING

My GPS (in HTC HD2) is mounted on my steering wheel using the universal adapter which is max 10;5 cm wide. Once adjusted to the size of my HTC HD2, I can take this one out for taking nice pictures and footprints while I am underway, and I can easily put it back to continue the ride.

USING GPS AND TAKING PICTURES

With the HTC HD2 I can take pictures, without closing CoPilot v8 application, so the GPS track recording is uninterrupted (I use this track for documenting my tour afterwards via the GPSVisualizer internet site)

Taking out and putting back the HTC HD2 takes a few seconds, and I prefer this all-in-one solution rather than having to carry and take care of two or three separate devices (Photo, GPS, Mobile). And with sufficient lighting, the 5 MPx pictures of the HTC HD2 are really sharp and wonderful.

Real photographers, of course, have a separate and much better camera and thus the GPS device needs not to be disconnected.

WHERE TO BUY
I ordered this via Rose Versand. It was much cheaper (109 EUR + 8 EUR for delivery in Basel) than buying it in Switzerland (249 CHF)

Here is the best offer from Rose Versand via internet in Germany (delivered without problem in Basel via normal post...

(situation: August 2011, but the price since March is unchanged) 

The price differences between Germany and Switzerland are enorm. Here the offer from VeloPlus shop in Basel ... of course I didn't buy here. (and they were not willing to give me a rebate either)